Highly active antiretroviral therapy (HAART) has revolutionized the therapy of human immunodeficiency virus disease, yet a substantial fraction of patients either never respond, or lose virologic control during the first 3 years of therapy. In this study, patients who have failed HAART are being treated with three experimental agents. The study has two major goals: to determine the response rate to these agents, and to determine what clinical and laboratory parameters, especially genotypic and phenotypic analysis, are useful for predicting response. Ultimately, a database of 300 patients is expected to be available for analysis.